Radio antenna construction



Feb. 6, 1940. c. A. UPSON 2,189,155

RADIO ANTENNA CONSTRUCTION Filed March 26, 1936 2 Sheets-Sheet l INVENTOR. CarZss 11%3020 Ais ATTORNEY.

Feb. 6, 1940. A UPSQN 2,189,155-

RADIO ANTENNA CONSTRUCTION Filed March 26, 1936 2 Sheets-Sheet 2 @arkszf @5522: BY g; 7 Q

%z.'s ATTORNEY.

Patented Feb. 6, 1940 Y 2,1895155 a is RADIO ANTENNA: CONSTRUCTION Charles A. Upson, LockportfN, Y., assignor, by ,mesne assignments, toGeneral Motors Gor poraticn, a corporation ofyDelaware I Applicatio nlMarch 26, l936, Se1fial it 11,001

(cilzsolta This invention relates to an antenna for use :particularlywith radio receiving sets mounted in automobiles or similar vehicles, although many features of the invention may be used also under 5 other conditions.- I. i v i I The provisionof a satisfactory antenna for radio receivers in an automobile presents a'prob- .lem of great difficulty. It was formerly possible i a. to build a reasonably satisfactory antenna in the Referring nowtothe diagram in Fig. 1

Q10 roofstructure of an automobile, but with the 1' recent trend toward making the roof of metal, :an antenna in the roof is no longer feasible.

It has also been proposed to use, as a -radio antenna, a series of wires supported between the axles of the automobile, or a wire or metal structure supported beneath the runningboard of 'theautomobile at a substantial distance below it 4 and insulated therefrom. Both of these pro- --posed forms of aiitenna are unsatisfactory, not

6 1s altransverse section similar to Fig; 3

showinga modified formfof construction;

Fig is .a pIan of the construction shown in Fig; 6, with parts removed; to show the 'construch j'tionbeneath, and

Fig...8. i,sl a -view similar ,to Fig.7? showing still ranothermodification. v

several; yiews indicate the sameparts The same reference numerals throughoutthe the drawings, the automobilebody is indicated at li and the ground ishsho'wnat [2." For any I .giv en; strength of ,radio'frequency field in which the automobile is placed a; given voltagemay be-considered as set up across thecapacity C1' 15,

between the car body and the ground. It, now, a metallic memberl3, such as the radio antenna hereafter described, be associated. With'the car 5b ,dy, it; is seen that there are two capacities Q2 only from an electrical standpoint, but also from Y a purely mechanical standpoint, as they are in an exposed or unprotected position so that they are hit by gravel or the like on the road surface,

41 and become coated with snow and :ice in the 322 winter. i

An object of. the invention is the provisionof i an improved radio antenna-which is'highly'eflicient both electrically and mechanically, which is protected from gravel or flying missiles,- and which avoids other defects inherent in ,previous antennae. v 1 'Z "Another object of the invention is the provision of an antenna which is relatively simple, easy, and inexpensive to construct, andwhich ,does 5 35 not present an unsightly appearance. I

.To these and other ends the invention resides in certain improvements and combinations' 'of' par-ts, all as will be hereinafter more fully de-.

trio

,lantenna of the preferred form and associated p s; I

Fig. 4 is a bottom; plan view of the preferred Qantenna construction with the. -bottomlayer lomitted to show the constructionabove;

i Fig. 5 is a fragmentary lon tudinal section substantially on the line 5 5 of, Fig.,e;.;

which may beconsideredas being in parallel zo ;,with the capacity 01,, namely; the capacity v.Ca

between the antenna element l3 and ,thebody ll, and thecapacity C3, between the .antenna g {element I3 and theground 1-2.. a The total voltage i 5 E1 therefore (divides into .;the compenents 113231. 25 .racross the .capacityCz, and E3 across the capacity I Ca. The sum of .the voltage components E2 and 5E3 ;Will equal thetotal voltage-E1, and the com:- ponentsiEaand Es will have. a relation to each I other inversely proportional to 'thecapacities C2o30' g. and C3.

. If the radio receiver, in the automobile is to be -should-be'as high aspossiblef The antenna of l a the present invention admirably fulfills these de- LAO sirable conditions, having low] capacity to the automobile body and high'capacity. tothe ground, awhile at the same time being fully protected not gonly from mechanical injury, but also from ice, .qssalt slush (now common'in cities where .salt is.c4 used for melting ice on streets) and other factors 1 which would tend to short circuit an antenna lain an exposed position. I

iReferring, .now to thegpreferred embodiment :shown in Figs. 2 to5, inclusivatthe automobilea5 body, here indicated in general. by the numeral ventiona1 metal construction, is mainly of some tr m ' insulating or dielectric material, such as wood I1,

inches- I which may be in a single thick layer, but which is preferably laminated. Because this wood panel ll is-thicker than the conventional steel running board, and because it is desired to maintain the top surface of the running board at the conventional standard height while still using supporting brackets [8 of standard height, it is preferable to notch or recess the panel as shown at [9, wherever'the brackets l8 occur.

On the bottom side of the dielectric panel I! are plates of conducting material, such as sheets of aluminum, copper, or th'e'like; It-is to be noted especially that one continuous plate the full length of the running board is preferably not employed, because there would be considerable electrical capacity between such a plate and the metal brackets it. Instead, a series of sections or separate platesare provided between the respective brackets I8 and also, if desired, between the ends of' the running'board and the nearest adjacent brackets. The metal antenna plates :are ,of such dimensions that they are spaced-edgewise'a considerable distance from all of the brackets l8, and also from the closest metal --frame members it and the metal mudguards 2|,

such spacing preferably being-at least 2' to 3 Jumpers orconnecting wires or strips 22, extending around the ends of the metal brackets is and spaced -a substantial distance therefrom,

are used to connect the various antenna sections 20 electrically'to each other. One of these sections is connected, in turn, to one terminal of .the radio receiving set indicated' diagram- .matically at 25, by means of a lead-in wire 26 which is spaccd a' substantial distance (prefer- .far as reasonably possible. -.of the radic setisconnected by a wire 21 to ably at least. 3 inches) from the closest bracket illand which is also jumped around the-metal frame member 15, being spaced therefrom as The other terminal the metal-parts of the vehicle frame.

" '..A.layer 30 0f dielectric material, such as one or more plies of wood, is placed beneath the antenna .p1ates .'2ll in covering relation thereto. .:This layer 30 is omitted or cut away at the points where the main panel I! is recessed for reception .of. the brackets 18. The space between the'dielectric members I! and 3t, beyond the edges of the conducting plates 20, is filled against entrance. of moisture at their. edges by resistant for all prac- The top surface ofithemember ll may be covered'by a rubber matting or the like 35. If the antenna members 20 are extended to the extreme outer edge of the running board, as is preferably the case and as shown in Figs. 3rand .4, then the rubber covering 351s preferably extendedaround the edge of the members ll and 3!! far enough'to completely .seal and protect the outer edges of the. antenna members. The c'onnectingwires 22 are also completely enclosed and protected in any suitable Way, as by running them in suitable grooves in the covering .35, or bylstopping the channels 19 short of the extreme outer edge of'the running board, leav- .ing at the outer edge a portion of the panel I! of full thickness, along the under side of which the wires 22 may run, and which wires may, like the plates 20, be covered by the bottom covering layer 30.

Itis now seen that the antenna is completely enclosed and thus protected mechanically from impacts of stones and the like. Furthermore, it is sealed in a substantially moisture-proof manner, so that itis not affected by iceor salt slush I accumulating on the bottom of the running board during winter driving. Moreover it fulfills admirably the desirable electrical conditions, the large flat plates 20 parallel to the ground hav ing a relatively high capacity to the ground, and yet having a relatively low capacity to the automobile body, not only because of their spacing away from all metal parts of the body, but also because they are presented edgewise to these metal parts, rather than fiatwise, thus again tending to decrease the capacity.

hrlnmany or most cases,'the antenna acts as a counterpoise rather than as a true aerial, the automobile body itself acting as the aerial. In

other cases, however, particularly where the automobile has a metal iloor which is relatively, ;low and a running board which is relatively high, .the' antenna parts, 20 may act as a true aerial,

the automobile body being the counterpoise. But in-either event, and particularlywhen the elhcient and satisfactory antenna construction results,"and the word antenna as used in the specification and in the accompanying claims is intended in a broad sense as including a construction whiehoperates either asa counterpoise or as an aerial.

It is further to be noted that the construction above described is preferably used in both running, boards, at vboth sicles of the automobile, and not merely in one running board. When the vehicle is thus provided with the prefer'redtype of runningboard antenna at both sidesoftheautomobile, with both sides connected tov the radio receiving set, it is seen that the antenna has practically no directional effect 1, because, it is not shielded to any substantial extentpfrom signals coming from any particular direction, I-Ience it will givesatisfactory reception irrespective of the way in which the autom'obile.;may be pointed with respect to the broad-' casting station. I v

.Since the antenna is entirely enclosed in the running board of the automobile, there are no unsightly or unfamiliar parts exposedto view. Indeed, the external appearance of the automobile isnot changed in the least when the vvantenna;of the present construction is used.

In Figs. 6 and 7 of the drawings there is illustrated a modified form of construction.

metalplates 20 act as a counterpoise, a veryri80 Here, asbefore the frame of the vehicle is indi-c cated at 'l6,and the running board supporting brackets are shown .at 18. :The main body of the'r'u'nning. board,,'as before, is made upof a panel ll of dielectric lmaterial, preferably of bottom of this panel ll, as in the previous embodiment, the present modification of the construction employs" a series of wires 40 running longitudinally along the running board in" grooves ll provided in either the upper or the -lowersurface of the panel ll, the upper surface being preferable. In either-event, the space in the grooves surrounding the wires is preferably Wood, either in a single layer or preferably lam-.1 'inated. Instead of'placing metal plates on the filled With'l'awateiproo'f sealing compound, and?! grouped close to the outer edge of the running tion of Figs. 6 and '7, except that here thin flat.

strips of copper or other metal are used, as indicated at Evil, in place of the wires ill. When these strips are relatively thin, it is not necessary to provide channels for them in the dielectric panel ll, but they may merely be placed on the top surface of the panel H, before the waterproof coating layer is applied. The connecting strip 52 connects the individual strips 50 to each other and it, or a wire connectedto it, runs to the radio receiving set. The strips 56, like thewires fill, are all grouped near the outer edge of the running board, to reduce capacity between them and themetal vehicle body. v

The modifications illustrated in Figs. 6, 7,and 8 are used .just like the preferred embodiment shown in Figs. 3, 4, and 5, and those modificarunning board, and the inner edge of this effective area of the antenna is spaced materially outwardly from the inner edge of the running board structure.

This application is a continuation in part of the copending application of Charles A. Upson, Serial No. 13,288, filed March 27, 1935, for patent on Radio antenna for automobiles.

While certain embodiments of the invention have been disclosed, it is to be understood that the inventive idea maybe carried out in a number of ways. This application is therefore not to belimited to the precise details described, but is intended to cover all variations and modifications thereof falling within the spirit of the inventionor thescope of the appended claims.

I claim: 1. A combined weight supporting step and radio receiving antenna for an automobile, comprising a running board structure projecting laterally from one side of the automobile body, said run-.- ning board structure including as an integral unit l two layers of substantially dielectric material,

and electrical conducting means interposed between and'encl'osedby said two dielectric layers,

said electrical conducting means being of' large area so as to have relatively great electrical capacity to ground and being spaced materially outwardly from the inner edgeof the running board to minimize capacity to the automobile body, said conducting means serving as a radio antennaand one of said layers of dielectric material being constructed and arranged to conelement.

stitute a platform capable of supporting the Weight of persons steppinginto and out of the automobile. l

' 2. A radio receiving antenna and load supporting step for an automobile, comprising a running board structure projecting laterally from one sideof the automobile body, said 1 running, board structure including a series of spaced supporting brackets twolayers of substantially dielectric material one of which is directly attached to and bridges the space between said brackets to constitute a weight supporting step, and a sheet of electrical conducting material interposed between and enclosed by said two dielectric layers, said sheet being of relatively large area so as to have relativelygreat electrical capacity to ground and having an inner edge spaced materially outwardly from the side. of said automobile body to minimize capacity to the body, said sheet serving as a radio antenna.

3. An automobile construction comprising, in combination, a frame and body structure, a plurality of brackets projecting laterally from said structure, a. running board including a plurality of plies of substantially dielectric material s cured to and supported by, said brackets, a plurality of metal sheets interposed between plies of said dielectric material, each of said sheets being spaced laterally from said brackets so that said sheets do not overlie the brackets, and conducting means connecting said sheets to each serve as a radio antenna.

4. A radio receiving antenna for an automobile, comprising arunning boardstructure projecting laterally from each of two opposite sides of the automobile body, each running board structure consisting oi two layers of substantially dielectric material constructed and arranged to provide a seli supporting step and electrical conducting means interposed between and enclosed by said two dielectric layers, said electrical conducting means in each running board structure being oflarge effective area so as to have relatively great electrical capacity to ground, and means electrically connecting said conducting means in one running board to said conducting means in the other running board and to a radio set'so thatsaid conducting means in bothrunning boards may serve conjointly as a receiving antennasubstantially unshielded by said automobile body and having little or no directional effect. l l

5. An assembled unit "for attachment to an automobile as a combined, running board and radio antenna comprising a series of spaced frame brackets, a main running board member constructed of dielectric material having grooves on cover of dielectric material cooperating with said member to completely enclose the signal pick up 6. An assembled unit for attachment to an automobile as a combined running board and radio antenna comprising a series of spaced atother and to a radio setso that said sheets may tachment brackets, a main weight supporting platform spanning the space between said brackets and being constructed of dielectric material, a signal pick-up element bearing against one face of said platform and a cover of dielectric material cooperating with the platform to comp letely enclose said pick-up element.

CHARLES A.'UPSON. 

